Method of producing capped steel



Feb 13, 194 0, H. R. BELDING I METHOD OF PRODUCING CAPPED STEEL FiledJune 16, 1938 Patented Feb. 13, 1940 UNITED STATES PATENT OFFICE2,190,393 I METHOD OF PRODUCING oArrEn STEEL Harvey Ross Balding,Sharpsville, Pa.

Application June 16, 1938, Serial No. 214,099

4 Claims. (01. 22-200) This invention relates to capped steel, one ofthe objects being to produce ingots that are the equal of thosemanufactured by conventional capping practice but which are less apt tobe 5 damaged in the soaking pits.

According to the invention, the degree of oxidation of molten steel tobe cast in the ingot mold andcapped is controlled so that whenthe steelis cast it neither rises nor falls in the mold l anyappreciable distanceduring a time interval at least 'sufiieient to permit capping. It is tobe understood that the steel is not killed. It should be'suflicientlyoxidized'to re- .main open in the mold whereby it would rim in theabsence of capping. Preferably, the degree of oxidation is controlledduring the working or the steel in the furnace and by treatment in theladle, but itis possible, and, in some instances, it may prove necessaryto makemold 20 additions for the purpose of adjusting the oxidation ofthe steel. Thus, aluminum added to the mold will check a fallingtendency, While sodium floride will halt undue rising.

This steel is cast, by means of a teeming ladle, 25 for instance, in asuitable ingot mold having an opening in its top exposing the moltenmetal. A bottle-neck ingot mold is considered most suitable. Aftercasting, the steel, which as previously explained is open, is closedwith a cap as 30. soon as possible after casting. It is to be understoodthat the function of the cap is to contact the molten ingot top and, byits rapid abstraction of heat from the steel, to quickly freeze a ,crustover the ingot top which prevents further 35 'gas evolution and hencemechanically kills the steel so that rimming ceases.

Since the steel does not rise in the mold, it

- is necessary to cast it to such a level as will permit the cap to dipinto the steel. This is 40 contrary to the usual practice of casting arising steel, positioning the cap and waiting for sealing by reason ofthe steel eventually rising against the cap bottom. It has the advantagethat it permits complete sealing of the ingot top almost 45 immediatelyafter casting. To permit proper dip- Ding of the cap into the steel, acap having a suitably shaped bottom should be used, that is to say,- acap having a bottom capable of depending into the neck'of thebottle-neck mold,

50 provided this type of mold is used.

The advantages involved by the described procedure are, among others,the provision of a thick skin over the blow-holes, thus positivelyassuring protection for the ingot blow-holes dur- 55 ing subsequentheating in the soaking pits and mechanical working; and a noticeablelack of segregation on the part of the metalloids, the metalloiddistribution approaching that of a chemically killed ingot,

In some instances it may be desirable to pro- 5 vide a rim thicker thanresults from theimmediate capping described, and, in such instances, thecapping may be delayed to provide time for rimming. As, soon as theingot top is sealed by the cap, this rimming stops, there being nodanger inany instance of providing aninade quate skin over theblow-holes, provided the degree of oxidation of the steel be such that,when cast, it neither rises nor falls any appreciable distance in themolds. However, metalloid segregation will be noticeable; that is tosay, more like a. rimmed steel ingot.

For emphasis, it is repeated that, in all cases, the steel herecontemplated is of the type which would rim if not capped, but whichneither rises nor falls while rimming due to the fact that the gasevolution proceeds "at a rate that is neither so rapid as to causefalling due to normal thermal contraction and loss of gaseousconstituents, nor so slowas to cause gas entrapment by the steel andsubsequent rising of the ingot metal.

When the-steel is capped immediately after being cast, high internal gaspressures develop which-might conceivably cause rupture of the ingot topand result in a dangerous break-out. This will not occur if the ingotcap is designed to freeze the top of the ingot in the form of a downwardspherical crust since the spherical shape is naturally adapted tomechanically withstand fluid pressure.

The accompanying drawing illustrates a cap designed to produce thisdownward spherical crust, Figure 1 showing the cap ready to be placedover the neck-opening of a bottle-neck mold, and Figure 2 showing thecap in place and the ingot steel capped by a frozen crust.

More specifically, this drawing shows a bottle-neck mold l into whichoxidized steel has been cast, the cap 3 for capping this steel having ahemispherical metal contacting bottom 3 of at least slightly lessdiameter than the neckopening 4 of the mold I.

The second figure shows the cap in use, the ingot metal being nowenclosed by a crust .5 constituting the rim usually associated with theinitial freezing of oxidized rimming steel, the top of the ingot beingsealed by a-crust 6 forming a continuation of the rim.'

Due to the cap being of slightly less diameter than the neck-opening ofthe mold, and due to the fact that, as illustrated by the first figure,the steel was cast to a level well up 1110 this neck, the sealing crustB encircles the almost perpendicular sides of the hemispherical bottomof the cap and firmly grips the same, due to thermal constriction. Thismechanically holds the cap in place and is a substantial aid in thepreven tion' of break-outs, since the cap is held in place so as tosupport the crust 6. Furthermore, this sealing crust is hemispherical inform due to the fact that it is frozen to form by the hemisphericalbottom of the cap. Therefore, as the gas pressure builds up in the steelin the mold, it is resisted by a hemisphere of solidified metal which,due to its form, is structurally strong, so that there is littletendency of this crust 6 to rupture.

In some instances, it may not be necessary to use a hemisphericalbottom. Thus, the principle of greater resistance to rupture may beincorporated in a cap having a rounded bottom that is not a trulyhemispherical shape but is only an approximation of the same.

I claim:

1. A method of producing a steel ingot, including casting aneffervescing steel into an ingot mold, the steel being oxidized to adegree preventing it from appreciably rising or falling in the moldafter its casting, the efferverscing of the steel being controlled bydipping a heat absorbing body into the top level of the steel while thistop level is molten throughout, the body providing a space between itandthe inside of the mold and displacing the molten steel into this'space to form a ridge of suilicient thinness to freeze substantiallyimmediately so as to efi'ect complete stoppage of the efiervescing ofthe steel.

2. A method of producing a steel ingot, includout.

ing casting an eflervescing steel into an ingot mold, the steel beingoxidized to a degree preventing it from appreciably rising or falling inthe mold after .its casting, the efiervescing of the steel beingcontrolled by dipping a heat absorbing body into the top level ofthe'steel, the body providing a space between it and the inside of themold and displacing the molten steel into this space to form a ridge ofsumcient thinness to freeze substantially immediately so as to effectcomplete stoppage of the efiervescing of the steel.

3. A method of producing a steel ingot, including casting anetfervescing steel into an ingot mold, the steel being oxidized to adegree preventing it from appreciably rising or falling in the moldafter its casting, the efiervescing of the steel bei'ngcontrolled bydipping a heat absorbing body into the top level of the steel, the bodyproviding a space between it and the inside of the mold and displacingthe molten steel into this space to form a ridge of sufiicient thinnessto freeze substantially immediately so as to effect complete stoppage ofthe efiervescing oi the steel, the steel contacting portion of the bodybeing shaped to freeze a downward, substantially' spherical crust on thesteel filling the space within the ridge.

4. A method of producing a steel ingot, including casting anefiervescing steel into an ingot mold, the steel being oxidized to adegree preventing it from appreciably rising or falling in the moldafter its casting, the efi'ervescing of the steel being mechanicallyhalted practically im medlately after its casting by freezing a gastight crust on the top level of the steel in the mold, this freezingbeing initiated at a time when this top level is molten practicallythrough- HARV-EY ROSS BELDING.

